Broken Varex controller? No worries! Alternative controller options.

[hybrid]

My Varex controller is maybe a few months old. One lady owner, rarely used - you know the deal.
Well it's stopped working now, which seems to be pretty common and why many end up just putting a manual switch in to control them.
Here is what the inside of your $100 Varex controller looks like.


This thing just uses two 5-pin relays (SRA-12VDC-CL) using both the Normally Open and Normally Closed contacts) to set the polarity of the motors inside the mufflers.
Oh, plus a $5 RXB3 wireless controller of course.

Press button A and wire 1 is 12V (+) and wire 2 is GND (-), opening the mufflers.
Press button B and wire 1 is GND (-) and wire 2 is 12v (+), closing the mufflers.

So to replicate this, all we need is a 2 channel 12V controller with relays that are 5 pin (having both NO and NC contacts).
I did some eBay searching and have found a couple of options - both for under $20.

This first option is a generic 2 channel remote switch.




The downside to this one is that they do not pick up the Normally Closed (NC) contacts on the relays. We can still use it though - we just need to solder wires to the contacts ourselves. I'll add another post when this arrives showing what to do.

The second option will work out of the box, as it's sold as a motor controller, but it's essentially the same thing (though a bit uglier). There will just be two relays inside switching polarity.



So for this one, give it your 12v and GND, connect up your varex motor wires and you're done.

$20 as opposed to $100 for exactly the same thing - albeit without the fancy varex casing.

[hybrid]

So not surprisingly, the "DC Motor Remote Controller" worked perfectly.
Cut off the Varex plug and replace with terminal connectors. Job done.



So how do you find this one?
Here's a direct eBay link that will probably end up broken.
https://www.ebay.com.au/itm/275604291741

But if you just search for "remote DC motor controller" you should be able to find it.
The user manual also calls it a TK005-2 controller.

[hybrid]

As expected, the second controller works with some minor mods too, which I will list here.

First thing we need to do is make the Normally Closed (NC) contacts useful since they aren't brought out to the terminal block.
If we look at the pinout below, we can see where the NC pin is located (5) and that it's connected to nothing on the back of the board.


So we put a link wire from the GND terminal to both of the NC pins on the back of the board. This means that when no button is pressed, both of the wires going to the motor are GND.
That's the soldering done.


The rest can be done using the terminal block.
We need to put a link wire from VCC (your 12v input) to each NO terminal.


That's it.
Now connect your motor wires to each COM terminal, and connect your 12V and GND wires to VCC and GND respectively.

So now when you press a button, one relay will change one of the COM terminals from GND to 12V (the other will stay GND) and turn the motor in one direction.
When you press the other button, the opposite COM terminal will change to 12V and turn the motor in the other direction.

Finished product:



You can see the polarity changing in the video below.